Various studies have shown that ecstasy (3,4-methylenedioxymethamphetamine) users display significant memory impairments,
whereas their performance on other cognitive tests is generally normal. The hippocampus plays an essential role in short-term
memory. There are, however, no structural human data on the effects of ecstasy on the hippocampus. The objective of this study
was to investigate whether the hippocampal volume of chronic ecstasy users is reduced when compared with healthy polydrug-using
controls, as an indicator of hippocampal damage. The hippocampus was manually outlined in volumetric MRI scans in 10 male
ecstasy users (mean age 25.4 years) and seven healthy age- and gender-matched control subjects (21.3 years). Other than the
use of ecstasy, there were no statistically significant differences between both groups in exposure to other drugs of abuse
and alcohol. The ecstasy users were on average drug-free for more than 2 months and had used on average 281 tablets over the
past six and a half years. The hippocampal volume in the ecstasy using group was on average 10.5% smaller than the hippocampal
volume in the control group (p=0.032). These data provide preliminary evidence that ecstasy users may be prone to incurring
hippocampal damage, in line with previous reports of acute hippocampal sclerosis and subsequent atrophy in chronic users of
this drug.